ryou

Hi all
I pulled my engine apart after an overheat lead to a blown water seal. The bearings have only about 100km on them, I wanted to know what kind of wear warrants replacing.

No copper showing through. Couple score lines just deep enough to catch on my fingernail. Can see marks similar to chatter marks? (see photos) Is this regular break in wear, or is it cause for concern? I would have followed the usual advice "Just replace it anyway" but Mazda quoted me $400 oz dollars for the full set!! So, given the wear I found, and say the clearance was ok once I measured it, would there be any issue reusing?


Front rotor. Score near the edge. Goes all around. There is another one near the oil groove, that one spans about 130 degrees of the bearing.

That patch with little to no wear? Is that a problem? (The scratches on that patch are from my fingernail)

Rear rotor.

Rear rotor. That little patch of wear like a bar code. Is that a cause for concern?

BLUE TII

iTrader: (9)

Those are good.

Mazda Motorsports cautions against replacing bearings unless something like ~50% of bearing is showing copper.

Reason os they are very soft and get distorted easily when pressing them in which creates tight spots that are prone to seizing.

Example, you have a patch with no wear on one and the "barcode" patch on another where it was scraped just putting the engine together.

A racer would just "flap" those with 800 grit and wd40 (putting 800 grit wet sand paper in split mandrel of die grinder and finding the rpm and angle that self centers the die grinder).

This removes high spots and puts a uniform finish on the bearing for less heat in the oil.

You have to THOROUGHLY clean after any abrasive machining and like any machining if you do ot wrong you destroyed your parts.

So, I say- best you run them as they are.

From Mazda Motorsports catalog tech tips-